earn (one's) keep
To perform sufficient work or help in exchange for money or housing. If you're going to live here rent-free, then you need to earn your keep by helping out with the cooking and cleaning. That boarder earns his keep by doing maintenance in the building.
earn one's keep
to help out with chores in return for food and a place to live; to earn one's pay by doing what is expected. I earn my keep at college by shoveling snow in the winter. Tom hardly earns his keep around here. He should be fired.